Dr. David Clark, Alma College – Wolf Spider Deception

In today’s Academic Minute, Dr. David Clark of Alma College reveals deceptive behavior found in male wolf spiders.

David Clark is Chair and Professor of Biology at Alma College in Alma, Michigan, where his research is focused on animal communication and the evolution of visual displays. His most recent research project examined habitat light characterization and visual displays in wolf spiders. He holds a Ph.D. from the University of Cincinnati.

Whenever animals communicate with each other, they are at risk of broadcasting information that may be intercepted by other animals. The unintended receivers of this information may be eavesdroppers, that is, members of the same species; or cue-readers, members of a different species, such as predators. We have found that, surprisingly, spiders are master eavesdroppers — a behavior mainly seen before in vertebrate animals. Their brains are literally the size of a pinhead, but male wolf spiders improve their odds of finding females by “eavesdropping” and initiating sexual displays whenever the courtship behavior of a rival male is detected.

A previous study found no evidence for eavesdropping in the brush-legged wolf spider, but the test males for this study were raised and matured in the laboratory. When we repeated this study with males collected from the field, we found that males demonstrated behavior consistent with eavesdropping, that is, increased interactive and courtship behaviors during and after video playback of a digitally produced courting male. In contrast to previous findings, field-collected males showed a significantly longer duration of interactive behaviors and more bouts of courtship activity when the digital male was present on the video screen.

Choice tests with two video screens showed that males recognize differences in male behavior; they responded to digital reproductions of courting male spiders more often and for a longer time than walking males or an empty leaf litter background with no spider.

These findings suggest that experience arising from field exposure to adult spiders from the same species may impact male eavesdropping behavior and social facilitation.